Today, artificial building material is one of the leaders in its field. High-strength concrete of different grades has outstanding characteristics. From it erect structures that are distinguished by reliability, durability and durability.
Concrete interacts well with reinforcing material. This tandem is highly appreciated in the construction of reinforced concrete structures. If you are interested in the question of what concrete is made of, then it is worth paying attention to 4 main components, among which:
- sand;
- cement;
- crushed stone;
- water.
These ingredients are added in certain proportions and play a role.
Main components
Concrete mixture, also called ready-mixed concrete, is a rolling stock of components that are mixed in a given proportion. If crushed stone is not added to the composition, then in the end you can get a traditional cement mortar, or sand concrete. However, in the latter, sand is used in a larger fraction.
To prepare the concrete mix , four parts of crushed stone, part of cement, two parts of sand and 0.5 parts of water are usually used. Quite often, beginning masters are interested in the question of what concrete is made of. This material can be considered with a specific example. To obtain it, 180 l of water, 1250 kg of crushed stone, 330 kg of cement and 600 kg of sand should be combined. These figures are approximate, but in reality the specific values will depend on many factors, among them it should be highlighted:
- brand of cement;
- brand of concrete;
- the use of plasticizers and other additives;
- characteristics of sand and gravel.
For example, if we take cement of the M400 grade for the mortar , then the use of the above ratio will allow us to obtain concrete M250. But cement of the M500 brand can be applied in the work, then the concrete brand in the final case will look like M350. When making concrete in a factory, dozens of characteristics and parameters are taken into account.
The role of the main components in concrete
If you also have a question about what concrete is made of, then you should become more familiar with the role of the main ingredients. Thus, water and cement act as the main components. They are entrusted with the main function, expressed in a bunch of ingredients in a single structure.
If you properly observe the proportions of these components, you will be able to complete the main task when mixing concrete. In construction, this ratio is called water-cement. We are talking here not only about the volume of liquid and cement, but also the humidity of the sand, as well as crushed stone and their water absorption.
When combined with water, cement begins to interact with it, which is called cement hydration. This component begins to set and harden, forming a cement stone. Many people came across this stone when they opened a bag of cement stored in the barn for several years.
Cement and water are already finished material. But when hardened, the cement stone is deformed. Shrinkage may be 2 mm per meter. This is a little, but due to the unevenness of the shrinkage processes, internal stress can occur, which contributes to the formation of small cracks. Although they are almost invisible, the durability and strength of cement stone are reduced. In order to reduce deformations, traditional aggregates are added to the composition, among them - sand and gravel.
The role of placeholders
Now you know what concrete is made of, but it’s important to know about the role of aggregates. Crushed stone is large, while sand is small. These ingredients are designed to create a structural framework that takes over shrink stresses during operation.
Ready concrete as a result gives not so impressive shrinkage. The strength becomes higher, under load, the deformation of concrete is reduced. Creep is reduced when the material is resized under continuous loads. To reduce the cost of concrete, aggregates are still needed. For the reason that cement is more expensive than sand and gravel, the last ingredients are simply necessary in the material.
Translation of weight fractions into volume fractions
At the very beginning of the article, you familiarized yourself with the proportions of the main ingredients of concrete. It will not be superfluous to translate into volume fractions and weight by making a calculation. This information will be useful to you if you are thinking about how to make concrete, the proportions need to be studied. If cement is taken in an amount of 0.25 m 3 , then water should be taken in a volume of 0.18 m 3 . The first ingredient is taken weighing 330 kg. The average bulk density of cement is 1300 kg per cubic meter.
As for water, it is taken in a volume of 180 liters. The weight of 0.9 m 3 of crushed stone with a bulk density of 1350 kg per cubic meter is 1250 kg. But 0.43 m 3 of sand is 600 kg of material, while the bulk density of this aggregate is 1400 kg per cubic meter.
If you have a question about what proportions to make concrete in, then you should familiarize yourself with the data presented above. But according to estimates, in the end you will be able to get 1.76 m 3 . You may be interested in the question of how all this fits into 1 cube of concrete. For an answer you need to take a liter jar and fill it with rubble up the neck. Between the stones there will be a lot of space called intergranular emptiness.
This void should be filled with two glasses of sand, a glass of cement and the same amount of water. All this is shaken and mixed, as a result of such manipulations you will get a dense substance. All pores of the material will be filled, the components will rub against each other. If concrete is not touched, then it will begin to harden. When mixing and vibrating, the material will again become plastic, will retain thixotropy.
It is important to mention a few words about a large aggregate - crushed stone. Its brand should be 2 times more, with regard to strength. This is true when compared with the design grade of concrete. This requirement is due to the fact that the design grade of concrete is lower in comparison with the real strength that the material gains after six months. But the strength of the rubble remains the same. Therefore, their leveling is necessary.
Additionally, the proportions of concrete made of cement M400
If you are still thinking about how to make concrete, the proportions of this material need to be considered more carefully. Using cement M400, you can get concrete of different grades, if you add the main ingredients: cement, sand and gravel in certain proportions.
To obtain concrete grade M100, components in the above sequence must be added in the following ratio: 1: 4.6: 7.0. But if there is a desire to get concrete grade M200, then cement, sand and gravel are added in the following proportions: 1: 2.8: 4.8. The highest grade of concrete is M450; to obtain it, the ingredients are added in the following respects: 1: 1.1: 2.5.
Foundation concrete preparation
If you have started building a house, you should know how to make concrete for the foundation. You need to take 10 kg of cement, 40 kg of crushed stone or gravel and 30 kg of sand. To obtain concrete grade M300 water should be added half as much as the weight of the remaining components. If the solution is too dense, then it can be diluted a little. It is better to adhere to a consistency that will allow mixing the liquid material with a shovel with the application of effort. That is, the solution should not drain off the shovel easily and quickly.
When asking a question about in what proportions to make concrete for the foundation, you should also answer yourself taking into account the fact that the sand may turn out to be damp. If it contains moisture, then before mixing the components, the fine aggregate should be dried or several liters of water taken. Sand should be checked for cleanliness. The cleaner it turns out, the better it will catch with the solution.
Additional recommendations
It is better to use gravel and crushed stone in a fraction within 2 cm. Cement should not be purchased long before construction begins, as it will absorb moisture during storage and will certainly deteriorate. It is recommended to do this about a week before the start of mixing the concrete mixture.
If we make concrete with our own hands, we must comply with the proportions. At the same time, pouring the foundation is best done in the warm season. When the temperature drops, you will have to heat the water and the solution so that it does not catch earlier. Otherwise, the material will turn out to be not so strong, in addition, it will not be tightly connected with the reinforcement or not compacted at all.
Use of concrete mixer for concrete preparation
If you decide to use a concrete mixer in the preparation of the mortar, it is important to make sure that the ingredients do not contain impurities. Crushed stone should be granite or gravel, only then the batch will turn out better.
Then the dry components are mixed together in a separate container. To do this, cement and sand are combined. A trough or bathtub is usually used for this. If you, too, are among those who are wondering how to make concrete in a concrete mixer, then at the next stage it is necessary to pour the resulting mass into a container where mixing will take place. However, gravel and water are added before this.
Methodology
Knead only after the last component is added - crushed stone. For a good kneading, it is advisable to take clean water, it should not contain salt. After completion of work, the concrete mixer is cleaned, there should be no mixture in it. To do this, water is poured inside and a little gravel is added. Mixing concrete in a concrete mixer is necessary until a uniform mass can be obtained.
Conclusion
Now you know how to make concrete in a concrete mixer, and in what proportions to add the main ingredients. You can use concrete mixers of various designs. Some of them are gravitational. In this case, the drum blades are responsible for mixing. The angle of the drum can be changed.
The second type of concrete mixers are forced action devices. Whatever equipment you use, the main thing is to mix the components in the correct proportions.